By then, the zoological society hopes to raise enough money or find other ways to keep the zoo running.
But the officials said they don't want to take any chances of legal complications from a sale to the zoological society.
Two years ago, the zoological society also tried to refocus itself in the public consciousness.
By 1930 a sizable collection of animals had been assembled and a zoological society formed.
He served as director of the zoo from 1913 to 1950 and as secretary to the zoological society.
While the Hagenbeck zoo was able to rebuild its animal trade, the zoological society could not.
In 1918-19 he was president of the German Zoological Society.
The zoological society will pay the excess cost.
"We're talking to the state and proposing that it purchase the zoo with the zoological society running it."
The city is paying for most of the renovations, and the zoological society is also providing funds.